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Go Back   SailNet Community > General Interest > General Discussion (sailing related)
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  #11  
Old 08-14-2006
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Remember folks -- wings draw considerably less than a fin keel. If the wing on my boat drawing 4'2" is aground, just think how deep into the muck a fin that draws 5'6" will be. I had just that experience not long ago at a big raft up. We had a severe thunderstorm that night, which swung the raft around and onto shallow water. The boats on either side of me drew 5'6" and were stuck fast. I was able to motor out from between them and took the main halyard to one of the boats in an attempt to heel him enough to get him off. Couldn't heel him enough to budge him. It took TowBoat/US to get both boats off.In short folks, you are much less likely to go aground with a wing in the first place compared to a fin. I know it's hard to accept, but at least have an open mind about it?????
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  #12  
Old 08-14-2006
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The problem I see with wing keels isn't that they're going to go aground all that often...it is that when they do go aground, you're usually in for a bear of a time trying to get unstuck.

I also notice that the wing keel advocates have quailifying statements in their posts—like "unless you're close to shore and/or inside a mark" or "tends to bounce off". However, unlike JeffH, neither says anything about when you do get stuck, and how bad it is when you do.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
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  #13  
Old 08-14-2006
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There is no doubt that a shallower keel will not run aground the same depth water as deep keel. That is 'Duh', but there are other ways to achieve a shallower draft besides a wing keel, including either a bulb keel or a keel centerboarder, and either is easier to unstick when aground.

For what it is worth, apropos to this discussion, I found myself in line ordering lunch behind a TowBoatUS operator. I asked what is his sense about wing keels vs fins on the Bay. He said that he tows off far more grounded wing keels than conventional keels, (Keel type is a question he asks since the freeing techiques are slightly different; wings he tries to pivot, while fins he tries to extract the way they went in) and that wing keel are much harder to get off of a grounding no matter what you do.

Yes, I know this is a very small scientific sampling.

Jeff
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  #14  
Old 08-14-2006
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There is a saying that if a boater claims he has never been aground he is either lying or hasn't had the boat long enough yet. I have been aground in all my boats except for the deepest draft boat. 6 years and not even touching the bottom. Perhaps just lucky. But the point is each boater uses their boat based on how deep their keel is. If you have shallow draft you go into shallower water. If you draw more water you are much more careful, and might not go aground as much as someone who needs shoal draft for the places they want to visit. Hence putting their boat in places where they are more likely to go aground.
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Old 08-14-2006
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Sorry to be such a contrarian on here about this little issue. My only intent is to shed some light on the usual knee jerk comments about winged keels since I've only sailed with them for 17 years. Yes, ground a wing really hard and it can be a bear to get off. Ditto for any keel that's really stuck. With a wing you have lots more options for places to go than someone with a fin as Gene T. points out, and on the Chesapeake that is a big plus. Perhaps I also have been lucky, but I have touched ground about a dozen times in those 17 years and have never been so stuck that I couldn't get off by myself. Sailing or motoring onto a shoal and getting cemented in place is not something I have experienced even once in those 17 years.
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Old 08-14-2006
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OK, since I have been identified as one of the advocates, I will retell something I posted here a long time ago. I have run aground once. Four years ago, when my boat was brand new, I was motoring down the Severn River toward Annapolis at night, doing five knots. My wife and I and another couple had sailed up to Round Bay, turned around and had a nice dinner while sailing back down. After we finished, it was getting late, the wind had died, so we decided to motor back with the main still up. I had the auto pilot engaged but was at the helm.

Nearly all of the marks in the Severn are lighted, with the exception of a green day mark a few hundred yards before the Route 450 bridge. My mistake was using the bridge as a guide instead of looking closely at the chartplotter. Drawing 4.5 feet, I plowed straight into 4.1 feet of water (according to the depth gauge) at five knots, enough to have the stern rear up a foot or two. When I realized what had happened I noted that I was near the green mark and was not far from 16 feet of water. It took me about 15 minutes to free myself, which I did by turning and motoring at low rpms. The boat would not move any better at 2500 rpms than it did at 1500, so I nudged forward, also repositioning the crew and the boom.

I don't advocate wing keels over any other type. Truth be told, I was going to get a fin keel on my boat (6.5 foot draft) for the performance but the dealer talked me out of it because of the general depth issues in the Chesapeake region and the possible difficulty I might have selling the boat in this area with the deeper draft keel. Yes, I did say one had to pay attention to the charts and marks and where the shoreline is, but any prudent sailor must do that regardless of what type of keel he or she has.
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Old 08-15-2006
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when's high tide ?

In ten years of frequent gunkholing on the Chesapeake I've had half the time on wing keels and half on a fin. I've grounded on both. Wind it comes to grounding they both have advantages over each other depending on the heel condition. Basically if you're motoring or sailing in very light winds, you're better off with the fin since in the worst case you can heel off. If you're sailing in strong winds, the wing gives you more warning by touching a wing tip and a better chance of getting out by dropping sail and leveling the keel.

Sailing heeled on the wing I have touched an edge several times and been able to get back out almost immediately. On the other hand the worst grounding I had was motoring a wing to an anchorage. It was very soft mud and she stood right up and could only be spun around but not moved otherwise. Fortunately we could just wait for high tide.

On a few other occasions I have motored a wing into one of those uncharted shoal spots and stopped in my tracks at 3 knots but not onto the shoal itself. Stopping at that speed is scary and not good for the boat or it's crew. We were still totally floating and could just turn or back from the shelf with no effort. We ran into the steep firmer mud instead of running up on it. I believe I've experience similar shoals with a fin which ended up slicing into the shoal and required much more expertise to get back off.

For the fin the worst case is sailing at full heel at a high tide. When she grounds you don't have much warning or more heel to work with. The momentum carries you further up the shoal and heels you even more ! In the motoring case I think you're better off with the fin since even if it slices in, you can heel it off if backing itself won't do. Plus you don't decelerate as fast with the generally smaller grounding surface area of the fin versus horizontal wing.

I find it interesting that the someone quotes the Navy study as favoring a bulb over a straight fin. I'd like to see the Navy's evaluation criteria since once on a shoal, he bulb has more surface area than the fin. I suppose they are assuming that the fin has deeper draft for the same righting moment so the bulb gets some plus points to offset the extra bulb surface area when trying to drag it off of a shoal. I helped someone with a bulb on a shoal once and it was not pretty. I previously had no problem getting my same depth fin off of the same shoal. If only we'd talked more the year between !

As far as sailing performance, the wing is a compromise between a deeper fin and a shoal draft. The performance can be expected to fall between the two also. The shoal draft has much more wetted surface than the deeper fin to get the same righting moment. Though a previous poster to this thread says the wing doesn't point as well that is contrary to what I've heard. What is clear is that the wing definitely pays a price off the wind with it's then useless extra wetted surface.

I haven't sailed much north of Annapolis, but I have gunked-holed to the edges of the chart clearances for my draft from Annapolis far south. All told, I think the skipper's experience and wisdom is more important than the type of keel. You need to know the strengths and weaknesses of each and when you are challenging these based on your current navigation. The less local knowledge I have, the more conservative is my navigation. That tends to keep me out of trouble more than the shape of the heavy thing under the boat.

Another performance related observation I've noticed is when tacking a wing and a fin. The wing can be made to dig the outer edge as you round the turn and turn sharper than the fin. With the wing you can actually make the boat heel outwards in the turn. Perhaps that's making too much turbulence and costing too much inertia. Tacking the fin I feel more like we're sliding around the turn. Not being a racer, I can't say if the ability to turn that sharp with a wing is an advantage in any way.

At this point I have a bias for the wing as I feel it best supports my cruising needs while giving better performance than the shoal draft. It lets me into shallower places than the fin and I'm not afraid of it. If I were a local racer I'd want the deep fin. Remember Australia II introduced the wing successfully as a rule beater against a comparable draft fin. If the two drafts are the same, the wing can beat the fin in some conditions. When heeled the wing acts like a deeper draft. If the Australia II had a shorter draft with the wing it would have lost. The cruiser case is the latter, a shorter wing draft versus a deeper fin.

Besides, when's the last time you even saw your keel ?
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  #18  
Old 08-15-2006
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A bulb keel is not as bad as a wing keel on a shoal, as heeling the boat can get a bulb keeled boat off the shoal, as the bulb doesn't increase draft as a general rule when you heel the boat, as a winged keel does.

A bulb keel can be much more efficient in terms of righting movement, compared to a fin keel. The bulk of the mass is at the very bottom of a bulb keel, whereas it is spread over the entire depth of the fin keel. The bulb can be a bit less draft than a fin keel with the equivalent righting moment. This means that a bulb keel boat may have a shallower draft while having the same righting moment.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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  #19  
Old 08-16-2006
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the bulb pays the piper too

Quote:
Originally Posted by sailingdog
...A bulb keel can be much more efficient in terms of righting movement, compared to a fin keel. The bulk of the mass is at the very bottom of a bulb keel, whereas it is spread over the entire depth of the fin keel. The bulb can be a bit less draft than a fin keel with the equivalent righting moment. This means that a bulb keel boat may have a shallower draft while having the same righting moment.
Ok, so if you reduce the draft by concentrating in a bulb you need to increase mass of the keel to make up for the shorter lever arm. On the other hand by shortening the fin to make the shallower bulb you've also reduced your lift area affecting pointing. What about that fatter profile for the bulb ? Isn't that more turbulence or at least more wetted surface without lift ? Maybe that is why I've seen some fin keels that taper outward as they go down, to concentrate weight lower like a bulb yet maintain some Bernoulli lift effects.

Last edited by captnnero; 08-16-2006 at 04:45 AM.
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Old 08-16-2006
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An article on keel design
http://www.boatus.com/goodoldboat/keeldesign.htm
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